1. Field of the Invention
This invention relates to large diameter tubular pneumatic transport using wheeled containers sometime known as pneumatic wheeled container transport or even tube vehicle systems. More particularly this invention relates to a propulsion system using air pressure having only one pipeline opened at both ends and only one propulsion unit placed at one end of this pipeline, this end being associated with the introduction of the wheeled containers inside of the said pipeline.
2. Prior Art
The large diameter pneumatic tubular transport using wheeled containers is a very old art and was proposed and implemented first by Latimer Clark in U.K. in 1865 (40" cross section, steel wheels, cargo transport--Battersea near London). Immediately after this, Alfred E. Beach built a large demonstrator prototype for passengers in U.S.
Lack of mass produced tubes, cheap electric energy and efficient air moving machinery in conjunction with the competition from the part of railway technology made the large diameter tubular transport to lay dormant till 1960-1964.
The modern large diameter wheeled pneumatics is started in Germany in 1960 (Kirchheim et All) for diameters ranging from 450 mm to 700 mm. The Kirchheim group developed and patented before 1970 almost all variants of containers, propulsion and auxiliary equipment (e.g. chains) used today in U.K. U.S.S.R., U.S., Japan (in Romania they use steel wheels).
The large tubular transport using wheeled containers was implemented industrially first time in the world in U.S.S.R. (1971) by Alexandrov, followed by Romania (H. Coanda & C. Teodorescu) and Japan (Nakamura). There are over 60 industrial installations built to date, the largest being of 50 km (U.S.S.R.).
Serious efforts are made in U.S.A., Canada, South Africa to implement this technology for bulk material handling.
The known usually used systems for propulsion of containers in pneumatic pipeline systems are using valves like flap valves, check valves, or gate valves involving or not servomechanisms to assure the necessary pressure for propulsion and letting the containers to pass the propulsion area.
The main disadvantage of these valves is the fact that the containers often smash them because they are not fast enough to let the containers to pass the propulsion area, and also the valve commutation is associated with large transients or even pushing the containers in reverse direction. Also, another big disadvantage of these valves is the fact that those which are servoactuated have a complicated structure implying hydro, electric or pneumatic subsystems not reliable in long term in heavy duty operation specially in remote unsupervised areas or involving low qualified personnel.
Another class of propulsion systems described in patent literature (U.S. Pat. No. 3,881,425) is using a pipeline and a series of boosters pumps (at least 2), that is propulsion units spaced along the pipeline and a series of booster relays. This succession of booster is aimed to operate a very long pipeline (say 500 miles). In this booster relays configuration the air is extracted from the upstream by a manifold, then reinjected downstream by another manifold, the containers being actually sucked by air from upstream and air pushed downstream. Between the said manifolds, there is a bypass area where the container is slowed down as stopped before being ejected downstream. In this bypass area, the containers tend to be reversed and this tendency is counteracted by an externally powered mechanism like a conveyor belt with a gently sloping upper flight which allows the containers to straddle, then to be ejected further downstream in the pipeline. In this case, the container is all the time in the pipeline being ejected from time to time from the bypass area.
In this multibooster configuration the boosters are placed somewhere on the pipeline eventually at the middle of it.
This system with bypass and multiboosters (U.S. Pat. No. 3,881,425) is better than others but still complicated because: has a pump area (in fact many of them), where containers have to stop, has two manifolds system to take air from upstream and inject it downstream, has at least two pump means located at spaced points along the pipeline. Also, it is unreliable because of the conveyor flight device which is not strong enough for the large forces developed by the pneumatic propulsion process. So this system actually involves different objects and structures along the pipeline obstructing the flow of containers which have to stop hence to lose kinetic energy in the propulsion process.
It is an object of this invention to provide a propulsion system which eliminates the need of many relay-boosters system of propulsion, flap valves or the like, reducing the propulsion unit to only one.
It is a further object of this invention to provide a propulsion system for continuous movement/flow of containers which is not wasting the kinetic energy of the containers simply by not stopping them when they pass the propulsion area.
It is yet a further object of this invention to provide a propulsion unit which reduces the number of manifolds reducing them to only one.
It is a still further object of this invention to provide a propulsion unit with a reliable strong system of moving containers in the propulsion area so that it to be able to face the usually huge counter forces experienced by the pneumatic propulsion process.
It is a still further object of this invention to use only pressure principle propulsion process.
It is a still further object of this invention to use pressure principle propulsion instead of suction and pressure.
It is a still further object of this invention to use only one continuous pipeline unobstructed along it by associated objects/structures or mechanisms.
The main object of this invention is to provide a propulsion unit which is simple in construction and relatively maintenance free.